❓ What?
The maximum or threshold percentage of disk space that can be used before an OSD is considered too full to backfill. This ratio is reached after crossing nearfull-ratio. Once utilisation crosses backfillfull-ratio, it reaches full-ratio. The default value is 0.90 or 90% of the total available space.
🎤 How?
The parameter is set during cluster creation in the OSDMap as:
[global]
[...]
mon_osd_backfillfull_ratio = 0.95Afterwards, it can be changed by running the following on the admin node:
ceph osd set-backfillfull-ratioOn croit, it can be changed by navigating to Maintenance → Full Ratios (at the bottom):
👓 References
https://docs.ceph.com/en/quincy/rados/configuration/mon-config-ref/#storage-capacity